A team of US scientists have discovered a group of human monoclonal antibodies that can neutralize a broad range of influenza A viruses, including the H5N1 avian influenza virus (Sui J et al. Nat Struct Mol Biol. 2009;16[3]:265-273).

The researchers screened a library of human antibodies against hemagglutinin, a protein on the viral surface that enables flu virus to attach to and enter target cells. They identified 3 antibodies that were active against H5N1 avian influenza viruses as well as seasonal H1N1 flu viruses and the strain that caused the 1918 influenza pandemic. X-ray crystallography of one of the antibodies bound to the H5N1 hemagglutinin revealed that part of the antibody was jammed into a pocket on the stem of the virus, preventing the viral shape-shifting needed for the virus to fuse its membrane with the host cell membrane.